To the Editor.
—In the June issue of the Archives (1981;141:951-953), Godeau et al described a patient with primary hyperparathyroidism associated with polycythemia and noted a remission of hypercalcemia and polycythemia after resection of a parathyroid adenoma. As mentioned by these authors, the nature of the link between hyperparathyroidism and increased erythropoiesis in that case was unclear; however, there are reports in the literature that support a direct relationship between these two entities. In 1949, Berlin1 described a similar patient who had primary hyperparathyroidism and polycythemia. Unlike the case of Godeau et al, the earlier patient did not survive long enough to determine whether treatment of the parathyroid disease would have resulted in hematologic remission.Several years ago, I was interested in the regulation of erythropoiesis and noted that drugs and hormones, including parathyroid hormone (PTH), that increased renal cyclic adenosine monophosphate levels possessed erythropoietic activity in an erythropoietin